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Three-element stressed Ge:Ga photoconductor array for the infrared telescope in space
Applied Optics
|August 20, 2010
Summary
Researchers developed stressed Germanium:Gallium (Ge:Ga) photoconductor arrays for space telescopes. These detectors show high responsivity and low noise under low-light conditions, crucial for infrared astronomy.
Area of Science:
- Astrophysics and Space Science
- Materials Science for Detectors
Background:
- Infrared astronomy relies on sensitive detectors for low-photon environments.
- Germanium:Gallium (Ge:Ga) photoconductors are vital for mid-infrared detection.
- Stressing Ge:Ga detectors can modify their performance characteristics.
Purpose of the Study:
- To fabricate and test a stressed Ge:Ga photoconductor array for space applications.
- To evaluate detector performance under simulated low-photon influx conditions.
- To investigate the effect of applied stress on Ge:Ga detector properties.
Main Methods:
- Fabrication of a three-element stressed Ge:Ga photoconductor array.
- Experimental testing at 2.0 K under low-photon influx (~10^5 photons/s).
- Application of stress using a cone-disk spring apparatus.
Main Results:
- Cutoff wavelength observed at ~180 micrometers.
- High responsivity (~100 A/W) and etaG (~1) achieved at 2 Hz chopping frequency.
- Noise Equivalent Power (NEP) below 5 x 10^-18 W/Hz^1/2 with low-noise amplifiers.
Conclusions:
- Stressed Ge:Ga photoconductor arrays are suitable for low-photon infrared space applications.
- Observed slow transient and nonlinear responses dependent on background photon influx.
- The etaG time constant showed a dependence on photon influx (proportional to N_ph^(-1/2)).
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